Struct TrackExtra 

pub struct TrackExtra { /* private fields */ }

Per-TrackInfo extras — the FFmpeg side of one track-table row.

Carries the stream’s Parameters, which is what opens a decoder for the track — through Self::clone_parameters, which is a deep avcodec_parameters_copy with no tie back to the format context, so a decoder outlives the demuxer that named it.

No Clone, and no Default. Both would have to go through ffmpeg_next’s Clone / Default for Parameters, which check neither the allocation nor the copy: safe public code could dereference a null destination or receive parameters that are quietly incomplete. Clone cannot report either, so this type does not implement it; Self::try_clone is the same copy with the answer a caller can act on, and Self::clone_parameters is the handoff a decoder actually needs. This crate shipped a derived Clone over the unchecked path once, reachable from safe code that just copied a track row, and closed it by removing the derive (see demuxer::tests::the_public_track_extra_copies_are_checked_too).

The message-carrier law is the second, independent reason Clone stays off: messages may be Clone, but Clone is always a refcount bump, never a deep copy, and avcodec_parameters_copy is not that. This crate shipped a hand-written, checked Clone here once too — through Self::try_clone, to satisfy a channel bound — and it came back out for the same reason: a consumer that needs to share the TrackInfo this type lives inside wraps it in Arc once, at the door, instead of paying a deep copy per consumer. Self::try_clone remains for the one caller that genuinely wants an owned duplicate of the codec parameters, which sharing a message is not.

disposition is the raw AV_DISPOSITION_* bit set, not ffmpeg_next::format::stream::Disposition. That type’s from_bits_truncate drops bits the linked build has no constant for, and this crate’s stance on bit sets is that every pattern is a value — the same reason PacketFlags reaches the wire as a number.

Implementations

impl TrackExtra

pub fn new( stream_index: i32, parameters: Parameters, ) -> Result<Self, DemuxError>

Constructs a TrackExtra from the stream index and its codec parameters. Everything else starts absent.

Fallible, and that is the point. Parameters::new() and Parameters::default() are safe constructors that hand back a null-backed value when avcodec_parameters_alloc fails, saying nothing; accepting one here would store a landmine that goes off later, in a copy, on a thread that has forgotten the allocator ever failed. Refusing it at the door is what lets every other method on this type — and every reader of Self::parameters — rely on there being parameters at all.

Not const fn: Parameters owns a heap allocation.

pub fn try_clone(&self) -> Result<Self, DemuxError>

A deep copy of this row, with the codec-parameter copy checked.

The fallible counterpart of the Clone this type deliberately does not implement — see the type’s own documentation for why.

pub fn clone_parameters(&self) -> Result<Parameters, DemuxError>

An owned deep copy of the track’s codec parameters — the handoff that opens a decoder for this track.

FfmpegAudioStreamDecoder::open(track.extra().clone_parameters()?, track.timebase()). Fallible because the copy is: an allocation failure here is the difference between a decoder that is not opened and one opened on parameters that are not the file’s.

pub const fn stream_index(&self) -> i32

Returns the source AVStream.index.

pub const fn disposition(&self) -> i32

Returns the raw AVStream.disposition bit set.

pub const fn start_time(&self) -> Option<i64>

Returns the stream’s start time in the track’s timebase, or None when the container does not carry one.

pub const fn frame_count(&self) -> Option<i64>

Returns AVStream.nb_frames when the container carries it.

pub const fn parameters(&self) -> &Parameters

Returns the stream’s codec parameters — the handle a decoder is opened from.

pub const fn with_disposition(self, value: i32) -> Self

Sets the disposition bits (consuming builder).

pub const fn with_start_time(self, value: Option<i64>) -> Self

Sets the start time (consuming builder).

pub const fn with_frame_count(self, value: Option<i64>) -> Self

Sets the frame count (consuming builder).

pub const fn set_disposition(&mut self, value: i32) -> &mut Self

Sets the disposition bits in place.

pub const fn set_start_time(&mut self, value: Option<i64>) -> &mut Self

Sets the start time in place.

pub const fn set_frame_count(&mut self, value: Option<i64>) -> &mut Self

Sets the frame count in place.

Trait Implementations

impl Debug for TrackExtra

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Hand-written because Parameters does not derive Debug. The medium and codec id are the two fields worth printing; the rest of AVCodecParameters is per-kind detail the track row already carries in typed form.